There isn't any paticular rules to adoptables really.
All you really need to do is create an image with them in and make
some rules of your own, and if you used lineart, you need to credit
it.
That's all really!
Character : - Naami (S15), by sky15
Name: Naami.
Name Meaning/Origin: Hebrew; It means "Pretty".
Gender: Mare.
Age: Young Adult; 3-4 years.
Parent(s): --...
Question : - Real life horses, by Kody56
It is allowed to make characters of famous horses like zenyatta but editing the bio a little bit
Thanks again!